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ABSTRACT: BACKGROUND AND SCOPE: Self-incompatibility (SI) in flowering plants ensures the maintenance of genetic diversity by ensuring outbreeding. Different genetic and mechanistic systems of SI among flowering plants suggest either multiple origins of SI or considerable evolutionary diversification. In the grasses, SI is based on two loci, S and Z, which are both polyallelic: an incompatible reaction occurs only if both S and Z alleles are matched in individual pollen with alleles of the pistil on which they alight. Such incompatibility is referred to as gametophytic SI (GSI). The mechanics of grass GSI is poorly understood relative to the well-characterized S-RNase-based single-locus GSI systems (Solanaceae, Rosaceae, Plantaginaceae), or the Papaver recognition system that triggers a calcium-dependent signalling network culminating in programmed cell death. There is every reason to suggest that the grass SI system represents yet another mechanism of SI. S and Z loci have been mapped using isozymes to linkage groups C1 and C2 of the Triticeae consensus maps in Secale, Phalaris and Lolium. Recently, in Lolium perenne, in order to finely map and identify S and Z, more closely spaced markers have been developed based on cDNA and repeat DNA sequences, in part from genomic regions syntenic between the grasses. Several genes tightly linked to the S and Z loci were identified, but so far no convincing candidate has emerged. RESEARCH AND PROGRESS: From subtracted Lolium immature stigma cDNA libraries derived from S and Z genotyped individuals enriched for SI potential component genes, kinase enzyme domains, a calmodulin-dependent kinase and a peptide with several calcium (Ca(2+)) binding domains were identified. Preliminary findings suggest that Ca(2+) signalling and phosphorylation may be involved in Lolium GSI. This is supported by the inhibition of Lolium SI by Ca(2+) channel blockers lanthanum (La(3+)) and verapamil, and by findings of increased phosphorylation activity during an SI response.
Annals of Botany 07/2011; 108(4):677-85. · 4.03 Impact Factor
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Bruno Studer,
Roland Kölliker,
Hilde Muylle,
Torben Asp,
Ursula Frei,
Isabel Roldán-Ruiz,
Philippe Barre,
Céline Tomaszewski,
Helena Meally,
Susanne Barth,
Leif Skøt, Ian P Armstead,
Oene Dolstra,
Thomas Lübberstedt
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ABSTRACT: Genetic markers and linkage mapping are basic prerequisites for marker-assisted selection and map-based cloning. In the case of the key grassland species Lolium spp., numerous mapping populations have been developed and characterised for various traits. Although some genetic linkage maps of these populations have been aligned with each other using publicly available DNA markers, the number of common markers among genetic maps is still low, limiting the ability to compare candidate gene and QTL locations across germplasm.
A set of 204 expressed sequence tag (EST)-derived simple sequence repeat (SSR) markers has been assigned to map positions using eight different ryegrass mapping populations. Marker properties of a subset of 64 EST-SSRs were assessed in six to eight individuals of each mapping population and revealed 83% of the markers to be polymorphic in at least one population and an average number of alleles of 4.88. EST-SSR markers polymorphic in multiple populations served as anchor markers and allowed the construction of the first comprehensive consensus map for ryegrass. The integrated map was complemented with 97 SSRs from previously published linkage maps and finally contained 284 EST-derived and genomic SSR markers. The total map length was 742 centiMorgan (cM), ranging for individual chromosomes from 70 cM of linkage group (LG) 6 to 171 cM of LG 2.
The consensus linkage map for ryegrass based on eight mapping populations and constructed using a large set of publicly available Lolium EST-SSRs mapped for the first time together with previously mapped SSR markers will allow for consolidating existing mapping and QTL information in ryegrass. Map and markers presented here will prove to be an asset in the development for both molecular breeding of ryegrass as well as comparative genetics and genomics within grass species.
BMC Plant Biology 01/2010; 10:177. · 3.45 Impact Factor
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ABSTRACT: Publication of the rice genome sequence has allowed an in-depth analysis of genome organization in a model monocot plant species. This has provided a powerful tool for genome analysis in large-genome unsequenced agriculturally important monocot species such as wheat, barley, rye, Lolium, etc. Previous data have indicated that the majority of genes in large-genome monocots are located toward the ends of chromosomes in gene-rich regions that undergo high frequencies of recombination. Here we demonstrate that a substantial component of the coding sequences in monocots is localized proximally in regions of very low and even negligible recombination frequencies. The implications of our findings are that during domestication of monocot plant species selection has concentrated on genes located in the terminal regions of chromosomes within areas of high recombination frequency. Thus a large proportion of the genetic variation available for selection of superior plant genotypes has not been exploited. In addition our findings raise the possibility of the evolutionary development of large supergene complexes that confer a selective advantage to the individual.
Genetics 10/2007; 177(1):597-606. · 4.01 Impact Factor
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ABSTRACT: We describe a candidate gene approach for associating SNPs with variation in flowering time and water-soluble carbohydrate (WSC) content and other quality traits in the temperate forage grass species Lolium perenne. Three analysis methods were used, which took the significant population structure into account. First, a linear mixed model was used enabling a structured association analysis to be incorporated with the nine populations identified in the structure analysis as random variables. Second, a within-population analysis of variance was performed. Third, a tree-scanning method was used, in which haplotype trees were associated with phenotypes on the basis of inferred haplotypes. Analysis of variance within populations identified several associations between WSC, nitrogen (N), and dry matter digestibility with allelic variants within an alkaline invertase candidate gene LpcAI. These associations were only detected in material harvested in one of the two years. By contrast, consistent associations between the L. perenne homolog (LpHD1) of the rice photoperiod control gene HD1 and flowering time were identified. One SNP, in the immediate upstream region of the LpHD1 coding sequence (C-4443-A), was significant in the linear mixed model. Within-population analysis of variance and tree-scanning analysis confirmed and extended this result to the 2118 polymorphisms in some of the populations. The merits of the tree-scanning method are compared to the single SNP analysis. The potential usefulness of the 4443 SNP in marker-assisted selection is currently being evaluated in test crosses of genotypes from this work with turf-grass varieties.
Genetics 10/2007; 177(1):535-47. · 4.01 Impact Factor
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ABSTRACT: The unique properties of Lolium/Festuca hybrids and their derivatives provide an ideal system for intergeneric introgression. At IGER a focus on the Lolium perenne/Festuca pratensis system is being exploited to elucidate genome organization in the grasses, determination of the genetic control of target traits and the isolation of markers for marker-assisted selection in breeding programmes.
Chromosome Research 02/2007; 15(1):105-13. · 3.09 Impact Factor
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Elizabeth S Jones,
Natalia L Mahoney,
Michael D Hayward, Ian P Armstead,
J Gilbert Jones,
Mervyn O Humphreys,
Ian P King,
Tsugutoshi Kishida,
Toshihiko Yamada,
François Balfourier,
Gilles Charmet,
John W Forster
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ABSTRACT: A molecular-marker linkage map has been constructed for perennial ryegrass (Lolium perenne L.) using a one-way pseudo-testcross population based on the mating of a multiple heterozygous individual with a doubled haploid genotype. RFLP, AFLP, isoenzyme, and EST data from four collaborating laboratories within the International Lolium Genome Initiative were combined to produce an integrated genetic map containing 240 loci covering 811 cM on seven linkage groups. The map contained 124 codominant markers, of which 109 were heterologous anchor RFLP probes from wheat, barley, oat, and rice, allowing comparative relationships between perennial ryegrass and other Poaceae species to be inferred. The genetic maps of perennial ryegrass and the Triticeae cereals are highly conserved in terms of synteny and colinearity. This observation was supported by the general agreement of the syntenic relationships between perennial ryegrass, oat, and rice and those between the Triticeae and these species. A lower level of synteny and colinearity was observed between perennial ryegrass and oat compared with the Triticeae, despite the closer taxonomic affinity between these species. It is proposed that the linkage groups of perennial ryegrass be numbered in accordance with these syntenic relationships, to correspond to the homoeologous groups of the Triticeae cereals.
Genome 05/2002; 45(2):282-95. · 1.65 Impact Factor
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ABSTRACT: We have been using the classical model long-day (LD) plant Lolium temulentum Ceres, which can flower after a single inductive LD treatment, to study the floral transition in grasses. Plants of L. temulentum have been grown in short days (SD), transferred to LD and apices isolated after SD and a number of LD treatments, before being examined by SEM. We have used these observations to focus on the changes which occur in gene expression during the first 6LD. RNA has been isolated from meristems and cDNA-AFLP used to compare gene expression between SD and LD treatments. A number of florally enhanced cDNA fragments were identified including one with homology to the flowering time gene CONSTANS (CO) of Arabidopsis thaliana. When this cDNA was mapped in L. perenne (perennial ryegrass), it mapped close to the major quantitative trait locus for heading date. However we do not believe the sequence is the Lolium CO-ortholog since it is much more similar to an Arabidopsis CO-like sequence than to CO itself and does not appear to exhibit a daily rhythm as observed for CO and some other CO-like sequences. In addition, and rather intriguingly, the gene seems to be most highly expressed in the outer most leaf sheath although we are also able to detect RNA in the meristem. Recently to help us understand the function of this CO-like gene, we have identified a T-DNA insertion in the A. thaliana equivalent of the gene but have yet to identify a phenotype.
Flowering Newsletter. 01/2002; 33((2002)):42-48.
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ABSTRACT: Linkage maps of perennial ryegrass were constructed from F2 and BC1-type populations using, predominantly, restriction fragment length polymorphism data based on heterologous probes used in mapping other grass species. The maps identified seven linkage groups, which covered a total of 515 cM (F2) and 565 cM (BC1). They were aligned using 38 loci identified in both populations (common loci) and a possible marker order for all mapped loci in either population was identified in an integrated map. The estimated recombination frequencies and map distances between adjacent common loci were compared between the two data sets and regions of heterogeneity identified. Overall, the common markers identified a map distance of 446 cM in the F2 population and 327 cM in the BC1 population, reflecting a higher recombination frequency in the former, although the difference was not evenly spread over the seven linkage groups. BBSRC RASP Initiative; EC FAIR CT98-4063
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ABSTRACT: Orphan crops are those which are grown as food, animal feed or other crops of some importance in agriculture, but which have not yet received the investment of research effort or funding required to develop significant public bioinformatics resources. Where an orphan crop is related to a well-characterised model plant species, comparative genomics and bioinformatics can often, though not always, be exploited to assist research and crop improvement. This review addresses some challenges and opportunities presented by bioinformatics in the orphan crops, using three examples: forage grasses from the genera Lolium and Festuca, forage legumes and the second generation energy crop Miscanthus. BBSRC
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ABSTRACT: A single chromosome of the grass species Festuca pratensis has been introgressed into Lolium perenne to produce a diploid monosomic substitution line (2n 2x 14). The chromatin of F. pratensis and L. perenne can be distinguished by genomic in situ hybridization (GISH), and it is therefore possible to visualize the substituted F. pratensis chromosome in the L. perenne background and to study chiasma formation in a single marked bivalent. Recombination occurs freely in the F. pratensis/L. perenne bivalent, and chiasma frequency counts give a predicted map length for this bivalent of 76 cM. The substituted F. pratensis chromosome was also mapped with 104 EcoRI/Tru91 and HindIII/Tru91 amplified fragment length polymorphisms (AFLPs), generating a marker map of 81 cM. This map length is almost identical to the map length of 76 cM predicted from the chiasma frequency data. The work demonstrates a 1:1 correspondence between chiasma frequency and recombination and, in addition, the absence of chromatid interference across the Festuca and Lolium centromeres.
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ABSTRACT: This book contains a compilation of offered papers presented at the main congress of the XX International Grassland Congress held in University College Dublin, Ireland from 26 June to 1 July, 2005. It is complemented by six other books arising from the XX IGC as listed on the back cover: the book of invited papers from the main congress and five books containing the proceedings of five satellite workshops held immediately after the main congress at locations in the UK and Ireland (Aberystwyth, Belfast, Cork, Glasgow and Oxford). The workshops were designed to facilitate more in-depth presentations and discussions on more specialised topics of worldwide significance. The main congress brought together scientists from many disciplines, policy makers, consultants and producers involved directly in grass production and utilisation, as well as people in associated industries. They discussed issues around the theme of the congress, Grasslands : a Global Resource. The congress programme was organised around three main thematic areas: - Efficient Production from Grassland. - Grassland and the Environment. - Delivering the Benefits from Grassland.
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ABSTRACT: Proceedings 25th EUCARPIA Fodder Crops and Amenity Grasses Section Meeting, Brno, Czech Republic, 1-4 September 2003 Improving the available energy in natural fodders is the most desirable way of increasing the nitrogen use efficiency of livestock production. Perennial ryegrass (Lolium perenne) shows considerable genetic variation for carbohydrate content. Most of the carbohydrate is water-soluble, but starch is also present in vegetative tissues and is useful because it is readily available in the rumen and persists during ensiling. The relationships between fructan and starch accumulation in ryegrass can be genetically dissected by QTL analysis. QTL for fructan and starch do not overlap, so starch and fructan may be independently selectable. Groups of genotypes from a mapping family were polycrossed in 2002 to produce marker selection lines for further research.
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ABSTRACT: Background Helitrons are a class of transposable elements which have been identified in a number of species of plants, animals and fungi. They are unique in their proposed rolling-circle mode of replication, have a highly variable copy-number and have been implicated in the restructuring of coding sequences both by their insertion into existing genes and by their incorporation of transcriptionally competent gene fragments. Helitron discovery depends on identifying associated DNA signature sequences and comprehensive evaluation of helitron contribution to a particular genome requires detailed computational analysis of whole genome sequence. Therefore, the role which helitrons have played in modelling non-model plant genomes is largely unknown. Results Cloning of the flowering gene GIGANTEA (GI) from a BAC library of the Pooideae grass Lolium perenne (perennial ryegrass) identified the target gene and several GI pseudogene fragments spanning the first five exons. Analysis of genomic sequence 5' and 3' of one these GI fragments revealed motifs consistent with helitron-type transposon insertion, specifically a putative 5'-A↓T-3' insertion site containing 5'-TC and CTAG-3' borders with a sub-terminal 16 bp hairpin. Screening of a BAC library of the closely related grass species Festuca pratensis (meadow fescue) indicated similar helitron-associated GI fragments present in this genome, as well as non-helitron associated GI fragments derived from the same region of GI. In order to investigate the possible extent of ancestral helitron-activity in L. perenne, a methylation-filtered GeneThresher® genomic library developed from this species was screened for potential helitron 3' hairpin sequences associated with a 3'-CTRR motif. This identified 7 potential helitron hairpin-types present between at least 9 and 51 times within the L. perenne methylation-filtered library. Conclusion This represents evidence for a possible ancestral role for helitrons in modelling the genomes of Lolium and related species. BBSRC
